Shifts in tense

If verbs in a passage refer to actions occurring at different times, they may require different tenses. Be careful, however, not to change tenses for no clear reason.

Shifts in mood

Be careful not to shift from one mood to another without good reason. The mood of a verb can be indicative (he closes the door), imperative (close the door), or subjunctive (if the door were closed).

The writer’s purpose is to give orders, but the original version shifts unnecessarily from the imperative to the indicative; the editing makes both verbs imperative.

Shifts in voice

Do not shift without reason between the active voice (she sold it) and the passive voice (it was sold). Sometimes a shift in voice is justified, but often it only confuses readers.

The original sentence shifts from the active (youths approached) to the passive (I was asked), so it is unclear who asked for the wallet. Making both verbs active clears up the confusion.

Shifts in person and number

Unnecessary shifts in point of view between first person (I, we), second person (you), and third person (he, she, it, one, or they) or between singular and plural can be very confusing to readers.

Is the writer making a general statement or giving advice to someone? Eliminating the shift eliminates this confusion.

Many shifts in number are actually problems with pronoun-antecedent agreement.